The overall purpose of this study is to investigate the biochemical aberrations in extrapyramidal disorders and to develop model systems for predicting the efficacy of antiparkinsonian drugs. Attention will be given to the possible role of various monoaminergic neuronal systems in mediating events related to extrapyramidal dysfunctions. To achieve these objectives model syndromes of extrapyramidal dysfunctions will be produced in monkeys by introduction of unilateral lesion in the ventro-medial tegmental (VMT) areas of the brain stem. Appropriate pharmacological manipulation will be used in these studies to determine the antiparkinsonian efficacy of various centrally acting drugs. A study on the effect of nigrostriatal degeneration on pre- and postsynaptic monoaminergic receptors will be carried out. BIBLIOGRAPHIC REFERENCES: A. Lieberman, T. Miyamoto, A. F. Battista and M. Goldstein. Studies on the antiparkinsonian efficacy of lergotrile. Neurology, 25(5), 459-462 (1975). A. Lieberman, M. Zolfaghari, D. Boal, H. Hassouri, B. Vogel, A. Battista, K. Fuxe and M. Goldstein. The anti-parkinsonian efficacy of bromocriptine. Neurology (1976).